Computed tomography detection systems have employed scintillation/photodiode (indirect conversion) detectors. With these detectors, X-ray radiation incident on a scintillator are absorbed by scintillating material thereof, which in turn emits light photons that are detected by a photodiode, which in turn generates a signal indicative thereof. The scintillating material has included full size crystals, ceramics, or garnets. Unfortunately, these structures are generally rigid structures, limiting their shape. These structures are also relatively expensive.
Energy discrimination is achieved through stacking layers of different scintillation materials, which absorb in different energy bandwidths of the X-ray radiation. The stack, in general, goes from lower energy absorbing layers closer to the incident X-ray radiation to higher energy absorbing layers nearer to the photodiode. However, each additional layer increases the thickness of the detector and the amount of scintillating material and requires a photodiode. Unfortunately, this increases the overall cost of the detector and, hence, the CT scanner.
Direct conversion detectors include a direct conversion material that directly converts incident X-ray radiation to electrical signals indicative of the energy of the X-ray radiation. An example of a direct conversion material is Cadmium Zinc Telluride (CZT). Unfortunately, present day direct conversion materials are expensive and made from a solid crystal such that their shape is rigidly bound to the crystalline structure of the chosen medium. Furthermore, it takes time to grow the crystal, which adds cost to the manufacturing the direct conversion detector.
In view of at least the above, there is an unresolved need for another detector configuration.